modelBuoyancy

Model to add buoyancy if there is a temperature inversion in the tank

Extends from TransiEnt.Basics.Icons.Block, TransiEnt.Basics.Icons.ThermalStorageBasic (Icon for thermal storage model).

Information

1. Purpose of model

Adds Buoyancy to a stratified storage.

2. Level of detail, physical effects considered, and physical insight

Convective energy flow is considered as heat flow of the same amount.

3. Limits of validity

Purely technical component without physical modeling.

4. Interfaces

heatPort[N_cv]: Gets the temperatures from the temperature layers and returns the heat flow due to boyancy back

5. Nomenclature

The input parameters

6. Governing Equations

(no equations)

7. Remarks for Usage

This model should be used to add buoyancy to a one dimensional water storage model.

8. Validation

9. References

This model is largely based on the model "Bouyancy" in the Modelica Buildings-library (https://github.com/lbl-srg/modelica-buildings.git)

10. Version History

Model revised by Pascal Dubucq (dubucq@tuhh.de) on Wed August 24 2016. Control volumes are now in intuitive order (1 = bottom, N_cv = top volume)

Model created by Tobias Ramm (tobias.ramm@tuhh.de) on Fri Mar 20 2015

Parameters

TypeNameDefaultDescription
Modelica.Units.SI.VolumeVVolume of tank
IntegerN_cv3Number of finite control volumes
Modelica.Units.SI.TimetauTime constant for buoyancy mixing
Modelica.Units.SI.Densityrho998Density, used to compute fluid mass
Modelica.Units.SI.SpecificHeatCapacityc_v4.2e3Specific heat capacity
RealkV*rho*c_v/tau/N_cvProportionality constant, since we use Delta_T instead of dH

Connectors

TypeNameDefaultDescription
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_aheatPortHeat input into the volumes

Components

TypeNameDefaultDescription
Modelica.Units.SI.HeatFlowRateQ_flowHeat flow rate due to buoyancy from segment i to i+1
Modelica.Units.SI.TemperatureDifference[N_cv - 1]Delta_TDriving Temperature difference between adjoining control volumes